A virtual array shaping method for a mathematical multi-beam spherical phased array antenna

Abstract

This invention discloses a virtual array formation method for a mathematical multi-beam spherical phased array antenna, comprising: controlling the geometric dimensions of subarrays to keep the influence of aperture transit time of array elements within the subarrays within an effective range, i.e., using phase compensation to complete beamforming within the subarrays without considering the influence of aperture transit time; and then completing beamforming of the spherical array antenna between subarrays in the active region using a time delay compensation method; wherein, only phase compensation is performed between array elements within a subarray, and time delay compensation is performed between subarrays. This invention can meet the beamforming requirements of broadband signals for digital beamforming spherical phased array antennas, and the implementation method is simple.

Description

Technical Field

[0001] This invention relates to the field of spherical phased array antenna technology, and in particular to a virtual array formation method for a mathematical multi-beam spherical phased array antenna. Background Technology

[0002] Digital multi-beam spherical phased array antennas have gained increasing attention in recent years as they can simultaneously track and control multiple targets in space across the entire airspace due to their multi-beam operation mode. This has made them a hot research area in the field of novel antennas.

[0003] A key technical challenge in the design of digital multi-beam phased array antennas is how to achieve digital beamforming. Traditionally, digital multi-beam phased array antennas form beams by adjusting the phase of the digital signals in each channel of the antenna to ensure that the phases of the received digital signals are consistent across all beams. Since signal processing using complex signal phase weighting is theoretically mature and simple to implement in engineering, this beamforming method is widely used in the engineering implementation of phased array antennas. However, this method has a problem: while adjusting only the channel phase works for narrowband signal beamforming, the presence of dispersion often causes signal distortion in broadband signal beamforming, leading to problems in backend signal processing. Therefore, for broadband signal beamforming, it is necessary to adjust the time delay difference between each channel. However, in practice, adjusting the signal delay consumes significant system resources, making it difficult to perform time delay processing on each channel in engineering practice. Summary of the Invention

[0004] In view of this, the present invention provides a virtual array shaping method for a mathematical multi-beam spherical phased array antenna. This method combines two beamforming methods: adjusting time delay difference and phase difference. It is applicable not only to digital beamforming of narrowband signals in digital multi-beam phased array antennas, but also to wideband digital beam signals. The virtual array shaping technology for mathematical multi-beam phased array antennas proposed in this invention aims to provide a simple, reliable, and easy-to-implement beamforming method for digital multi-beam phased array antennas. This method does not require any external equipment and is applicable to both wideband and narrowband signals, facilitating the design of digital multi-beam phased array antenna systems that meet performance requirements in engineering practice.

[0005] This invention discloses a virtual array formation method for a mathematical multi-beam spherical phased array antenna, comprising:

[0006] The geometric dimensions of the subarray are controlled to keep the impact of the aperture transit time of the array elements within the subarray within an effective range. That is, the effect of aperture transit time does not need to be considered within the subarray, and the beamforming within the subarray is completed by using the phase compensation method. Then, the beamforming of the spherical array antenna is completed between the subarrays in the active area by using the time delay compensation method. Among them, only phase compensation is performed between the array elements within the subarray, and time delay compensation is performed between the subarrays.

[0007] Furthermore, controlling the geometry of the subarray to keep the aperture transit time of the elements within the subarray within an effective range includes:

[0008] The angle between the incoming wave direction of the subarray on the boundary of the activation region and the normal of the subarray, i.e., the activation region angle θ. A The aperture transit time is the largest, meaning the aperture transit time of the subarray at the boundary of the activated region is the largest. The aperture transit influence factor K at this subarray is calculated to determine the geometric size of the subarray.

[0009] Further, the calculation of the aperture transit influence factor K at the subarray to determine the geometric dimensions of the subarray includes:

[0010] Based on the transmit and receive signal bandwidth B of the antenna design, the active region angle θ of the digital beam spherical phased array antenna is... A The aperture crossing influence factor K is obtained by taking the size of the array and the maximum distance d between the array elements in the subarray.

[0011] The geometric dimensions of the subarray are calculated based on the aperture transit influence factor K.

[0012] Furthermore, the aperture transit influence factor K is obtained through the following formula:

[0013]

[0014] The maximum distance d between elements in a subarray can be obtained using the following formula:

[0015]

[0016] Where c is the speed of light.

[0017] Furthermore, the method of employing phase compensation to complete beamforming within the subarray includes:

[0018] Suppose a subarray contains n elements: X1, X2, ..., X n With the center point O of the subarray as the reference, the kth element X of the subarray... k The phase difference between the transmitted and received signals and the center point O is the phase compensation value ΔΦ(X). k Based on the phase compensation value of the subarray, beamforming of all array elements within the subarray is completed.

[0019] Furthermore, the beamforming of all elements within the subarray based on the phase compensation value of the subarray includes:

[0020] The beamforming signal within the subarray is obtained using the following formula:

[0021]

[0022] Among them, S 子阵 (t) represents the beamforming signal of the subarray, S k (t) represents the transmit and receive signals of the k-th element in the subarray.

[0023] Furthermore, the beamforming of the spherical array antenna by using a time delay compensation method among the subarrays within the activated region includes:

[0024] The subarrays within the active region are compensated for time delay by compensating the spatial time delay of the transmitted and received signals of each subarray to the same value. Geometrically, this is equivalent to virtually placing each subarray within the active region on an array surface perpendicular to the transmitted and received signals, and then performing beamforming on that array surface.

[0025] Furthermore, the beamforming of the array includes:

[0026] The coordinates of the beam pointing point on the array surface corresponding to the active region of the spherical array antenna are (x0, y0, z0). The active region contains m subarrays: Z1, Z2, ..., Z h ,…,Z m ; with subarray Z h Center point coordinates (x h ,y h ,z h ) is a subarray Z h The coordinates; with the beam pointing point as the reference, subarray Z h The time delay difference between the transmitted and received signals and the beam pointing point is the time delay compensation value Δτ. h Based on the time delay compensation values ​​of the received and transmitted signals of each subarray, beamforming of all subarrays on the array surface is completed.

[0027] Furthermore, the beamforming of all subarrays on the array surface based on the time delay compensation values ​​of the transmitted and received signals of each subarray includes:

[0028] Beamforming of all subarrays on the array surface is achieved using the following formula:

[0029]

[0030] Among them, S 合成 (t) represents the synthesized signal of all subarrays in the activation region, S 子阵h(t) represents the transmit and receive signals of the h-th subarray in the activated region.

[0031] Furthermore, within a subarray, the maximum distance between array elements is set as the subarray length. The active region of the digital beam spherical phased array antenna is a cone formed by taking the center of the spherical array as the vertex, the beam direction as the central axis, and the angle between the beam direction and the central axis as the active region angle. In other words, an area is divided on the antenna array surface, namely the active region. The active region angle is the angle between the incoming wave direction of the subarray on the boundary of the active region and the normal of the subarray.

[0032] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0033] 1. This invention solves the problem of beamforming wideband signals in digital multi-beam spherical phased array antennas. It determines the maximum subarray size of the spherical phased array antenna based on a specific relationship between signal bandwidth and transit time. By performing phase compensation-based beamforming between elements within a subarray and time delay compensation-based beamforming between subarrays, the beamforming of the spherical array antenna is ultimately achieved. This method fulfills the beamforming requirements of digital multi-beam spherical phased array antennas for wideband signals, solving a key problem in the design of digital multi-beam spherical phased array antenna systems.

[0034] 2. Simple implementation, low resource consumption, and reduced system design costs. This invention does not require complex circuits, making its implementation relatively simple. It utilizes only existing system equipment without adding any extra devices, and uses software algorithms to achieve the virtual array formation function of the phased array antenna system, facilitating automated operation and reducing system design costs.

[0035] 3. Traditionally, digital multi-beam phased array antennas typically employ beamforming methods that use complex signal phase weighting for channel signals. However, due to the aperture crossing effect in phased array signal synthesis, for broadband signals, using only channel phase weighting beamforming results in signal distortion, affecting backend signal processing. Therefore, this phase weighting beamforming method is not suitable for broadband signals. The method of this invention can meet the beamforming requirements of digital multi-beam spherical phased array antennas for broadband signals; using this method, a digital multi-beam phased array antenna system that meets the performance requirements can be designed in engineering practice. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0037] Figure 1 This is a schematic diagram of beamforming in a traditional digital multibeam spherical phased array antenna.

[0038] Figure 2 This is a schematic diagram of the virtual array formation of a digital multi-beam spherical phased array antenna according to an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of the subarray structure of the digital multibeam spherical phased array antenna according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram illustrating the calculation of subarray transit time for a digital multibeam spherical phased array antenna according to an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the phase-compensated synthesized beam within a subarray of a digital multi-beam spherical phased array antenna according to an embodiment of the present invention.

[0042] Figure 6 This is a schematic diagram of the inter-subarray time delay compensation synthesized beam of the digital multi-beam spherical phased array antenna according to an embodiment of the present invention.

[0043] Figure 7 This is a schematic diagram of the beamforming algorithm for virtual array formation of a digital multibeam spherical phased array antenna according to an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0045] See Figure 1 In engineering practice, subarrays are typically polyhedral planar arrays, and multiple subarrays are ultimately pieced together to form a spherical phased array antenna. For example... Figure 1As shown, a digital multi-beam spherical phased array antenna activates subarrays within a circular region on the sphere, centered on the beam direction, to participate in beamforming. Each subarray contains multiple independent transmit and receive elements. When the beam of a digital multi-beam spherical phased array antenna is directed towards a target, the path lengths of the transmitted and received signals between the various elements within its activated region and the target differ, resulting in a path difference, or spatial delay difference between the transmitted and received signals. This spatial delay causes inconsistent phase shifts of the signal at different frequencies within the signal bandwidth, i.e., aperture crossing. For narrowband signals, the phase difference caused by the spatial delay difference of each element within the activated region of the spherical phased array antenna at various frequencies within the signal bandwidth is small and negligible. Therefore, traditional beamforming algorithms only compensate for the phase of each subarray element. However, for broadband signals, the phase difference caused by the spatial delay difference of each element at various frequencies within the signal bandwidth is large. Therefore, the aperture crossing phenomenon of the phased array antenna signal cannot be ignored, meaning that traditional phased array antenna beamforming methods are not suitable for broadband signals.

[0046] See Figure 2 and Figure 3 This invention employs a virtual array shaping technique to solve the beamforming problem of broadband signals in digital multi-beam spherical phased array antennas. Since the aperture transit time is related to the spacing between array elements, we can control the geometry of the subarrays to keep the impact of the aperture transit time of the elements within a subarray within an effective range. That is, within a subarray, the effect of aperture transit does not need to be considered, and phase compensation is used. Between subarrays, due to the unavoidable effect of aperture transit, a time delay compensation method is used. This involves compensating the spatial time delay of the transmitted and received signals of each subarray to the same value. Geometrically, this is equivalent to virtually placing each subarray within the active region on an array surface perpendicular to the transmitted and received signals. Figure 2 As shown, by compensating for the spatial time delay of each subarray, the subarrays within the active area of ​​the digital multi-beam spherical phased array antenna are virtually transformed into a spatial planar array perpendicular to the beam direction.

[0047] like Figure 3 As shown, beamforming consists of two steps. First, the subarrays within the active region are combined into a composite signal using the phase compensation method within the subarrays. Then, the subarrays within the active region are combined into the final beam signal using the time delay compensation method.

[0048] See Figure 4 and Figure 5 Based on the transmit and receive signal bandwidth B of the antenna design, the active region angle θ of the digital beam spherical phased array antenna is... A The size of the aperture and the aperture transit influence factor K are used to calculate the geometric dimensions of the subarray design. Figure 3 As shown, in a subarray, the maximum distance d between array elements is set as the subarray length. Figure 4 As shown, the active region of the digital beam spherical phased array antenna is defined by the center of the spherical array as its vertex, the beam direction as its central axis, and the angle θ between the beam direction and the central axis as the active region angle. A This forms a cone shape that defines a region on the antenna array surface. For example... Figure 5 As shown, the angle between the incoming wave direction and the normal of the subarray at the boundary of the active region is the largest. Therefore, the aperture transit time of the subarray at the boundary of the active region is the largest. Thus, we only need to calculate the aperture transit influence factor K at that location to determine the geometric dimensions of the subarray. The algorithm is as follows:

[0049] according to

[0050]

[0051] The largest possible size of the subarray is:

[0052]

[0053] Where c is the speed of light, and the aperture transit influence factor K is K≤0.2.

[0054] For example: Take B = 100MHz, θ A With an angle of 45 degrees and K = 0.2, the maximum size of the subarray is d = 0.85 meters. Subarrays designed in this way can disregard the effects of aperture crossing, and beamforming within the subarray can be achieved using phase compensation.

[0055] See Figure 6 ,like Figure 6 As shown, suppose a subarray contains n array elements: X1, X2, ..., X n With the center point O of the subarray as the reference, any element X of the subarray... k The phase difference between the transmitted and received signals and the center point O is the phase compensation value ΔΦ(X). k Therefore, the beamforming algorithm within the subarray is as follows:

[0056]

[0057] Among them, S 子阵 (t) is the synthesized signal of the subarray, S k (t) represents the transmit and receive signals of the k-th element in the subarray.

[0058] See Figure 7 ,like Figure 7 As shown, let the coordinates of the beam pointing point on the array surface of the spherical array antenna be (x0, y0, z0), and the beam activation region contain m subarrays: Z1, Z2, ..., Z m For any submatrix Z h The coordinates of the center point of the subarray (xh ,y h ,z h The coordinates of this subarray are shown below. With the beam pointing point as the reference, the subarray Z... h The time delay difference between the transmitted and received signals and the beam pointing point is the time delay compensation value Δτ. h Therefore, the beamforming algorithm between subarrays is as follows:

[0059]

[0060] Among them, S 合成 (t) represents the synthesized signal of all activated subarrays, S 子阵h (t) represents the transmit and receive signals of the h-th subarray in the activation subarray.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for virtual array formation of a mathematical multi-beam spherical phased array antenna, characterized in that, include: The geometry of the subarray is controlled to keep the impact of the aperture transit time of the array elements within the subarray within an effective range. That is, the effect of aperture transit time does not need to be considered within the subarray, and a phase compensation method is used to complete the beamforming within the subarray. Then, the beamforming of the spherical array antenna is completed between the subarrays in the active region using a time delay compensation method. Among them, only phase compensation is performed between array elements within the subarray, and time delay compensation is performed between subarrays. The control of the geometry of the subarray to keep the effect of the aperture transit time of the array elements within the subarray within an effective range includes: The angle between the incoming wave direction of the subarray on the boundary of the activation region and the normal of the subarray, i.e., the activation region angle θ. A The aperture transit time of the subarray at the boundary of the activated region is the largest. The aperture transit influence factor K at this subarray is calculated to determine the geometric size of the subarray. The calculation of the aperture transit influence factor K at the subarray to determine the geometric dimensions of the subarray includes: Based on the transmit and receive signal bandwidth B of the antenna design, the active region angle θ of the digital beam spherical phased array antenna is... A The aperture crossing influence factor K is obtained by taking the size of the array and the maximum distance d between the array elements in the subarray. Calculate the geometric dimensions of the subarray based on the aperture transit influence factor K; The method of employing phase compensation to complete beamforming within the subarray includes: Suppose a subarray contains n elements: X1, X2, ..., X n With the center point O of the subarray as the reference, the kth element X of the subarray... k The phase difference between the transmitted and received signals and the center point O is the phase compensation value ΔΦ(X). k Based on the phase compensation value of the subarray, beamforming of all elements within the subarray is completed. The step of beamforming the spherical array antenna by using a time delay compensation method among the subarrays within the activated region includes: The subarrays within the active region are compensated for time delay by compensating the spatial time delay of the transmitted and received signals of each subarray to the same value. Geometrically, this is equivalent to virtually placing each subarray within the active region on an array surface perpendicular to the transmitted and received signals, and then completing the beamforming of that array surface. The beamforming of the array includes: The coordinates of the beam pointing point on the array surface corresponding to the active region of the spherical array antenna are (x0, y0, z0). The active region contains m subarrays: Z1, Z2, ..., Z h ,…,Z m ; with subarray Z h Center point coordinates (x h ,y h ,z h ) is a subarray Z h The coordinates; with the beam pointing point as the reference, subarray Z h The time delay difference between the transmitted and received signals and the beam pointing point is the time delay compensation value Δτ. h Based on the time delay compensation values ​​of the received and transmitted signals of each subarray, beamforming of all subarrays on the array surface is completed.

2. The method according to claim 1, characterized in that, The aperture transit influence factor K is obtained using the following formula: The maximum distance d between elements in a subarray can be obtained using the following formula: Where c is the speed of light.

3. The method according to claim 1, characterized in that, The beamforming of all elements within the subarray, based on the phase compensation value of the subarray, includes: The beamforming signal within the subarray is obtained using the following formula: Among them, S 子阵 (t) represents the beamforming signal of the subarray, S k (t) represents the transmit and receive signals of the k-th element in the subarray.

4. The method according to claim 1, characterized in that, The beamforming of all subarrays on the array surface is completed based on the time delay compensation values ​​of the transmitted and received signals of each subarray, including: Beamforming of all subarrays on the array surface is achieved using the following formula: Among them, S 合成 (t) represents the synthesized signal of all subarrays in the activation region, S 子阵h (t) represents the transmit and receive signals of the h-th subarray in the activated region.

5. The method according to any one of claims 1-4, characterized in that, In a subarray, the maximum distance between array elements is set as the subarray length. The active region of a digital beam spherical phased array antenna is a cone formed by taking the center of the spherical array as the vertex, the beam direction as the central axis, and the angle between the beam direction and the central axis as the active region angle. In other words, an area is divided on the antenna array surface, which is the active region. The active region angle is the angle between the incoming wave direction of the subarray on the boundary of the active region and the normal of the subarray.

Images